Provide a sort of plugin system so that people can develop extensions that can be distributed and consumed easily.
I assume you want discussion here about how the extensions api would work. I've got use cases for extensions that I will evaluate against the ideas discussed.
That's right. Though I think this feature should land in 0.2.5 or 0.3.0 as 0.2.4 needs to get published ASAP.
One feature that could qualify as a plugin to me is abbreviated attributes.
One I'm not sure if should be a plugin or a builtin is stylus support (and markdown, and textile, and sass, and less...).
Some things to bear in mind, off the top of my head:
CK runs on the browser too. Each additional feature adds to coffeekup.js download size, and potentially (even worse) to each compiled template function.
Currently coffeekup.coffee is the final coffeekup.js, without modifications, on both node.js and the browser. I think this is desirable to keep.
CK is not a language. It's a library that allows HTML-resembling CoffeeScript functions to output a string (with the equivalent document) when run. So real language extensions are not possible, only clever exploits of the existing CoffeeScript syntax.